when jumping a car which car goes first

[SanJulianna]

When jump-starting a car, you should always connect the red, positive (+) cable clamp to the dead battery's positive terminal first. This initial connection is the safest starting point. After that, connect the other red clamp to the positive terminal of the good, live battery. Then, attach the black, negative (-) cable to the good battery's negative terminal. Finally, for the last connection, clamp the remaining black cable to an unpainted metal surface on the dead car's engine block or chassis—not the dead battery's negative terminal. This final step away from the battery minimizes the risk of sparking near potential battery gases, which could cause an explosion.

The correct order is crucial because it systematically manages electrical flow and potential hazards. A car battery can release hydrogen gas, which is highly flammable. By making the final connection to a grounded metal part away from the battery itself, any small spark that occurs when completing the circuit is kept at a safe distance. This "positive to positive, negative to ground" sequence is the standard recommended by every major automotive association and vehicle manufacturer for a reason: safety.

Here is a quick reference table for the correct, safe connection sequence:

Step	Cable Color	Connection Point	Rationale
1	Red (+)	Dead Battery's Positive Terminal	Establishes the primary circuit path safely.
2	Red (+)	Good Battery's Positive Terminal	Completes the positive side of the circuit.
3	Black (-)	Good Battery's Negative Terminal	Provides the ground source.
4	Black (-)	Unpainted Metal on Dead Car's Engine	Grounds the circuit away from battery, preventing spark-related explosion.

Once the cables are securely connected, start the car with the good battery. Let it run for a minute or two to transfer some charge. Then, try to start the car with the dead battery. If it starts, carefully disconnect the cables in the reverse order: black from the ground on the jumped car, black from the good battery, red from the good battery, and finally, red from the previously dead battery.

[HadleyFitz]

Positive on the dead battery first, always. That's the rule my dad drilled into me. Hook up the red clamp to the dead car's positive terminal. Then the other red to the good battery's positive. Next, black to the good battery's negative. For the last black clamp, find a shiny metal bolt or bracket on the dead car's engine—anywhere but the dead battery's negative post. That last part keeps any spark away from the battery. After the car is running, just take the cables off in the exact opposite order.

[Darren]

The most critical safety step is the final connection. You connect the positive cables to both batteries first. Then, attach the negative to the good battery. For the last negative clamp, you must connect it to a bare metal part of the engine block or chassis of the disabled vehicle. This provides a ground connection that completes the circuit without creating a spark directly above the battery, where hazardous gases can accumulate. This simple act of grounding the last cable away from the battery itself is what prevents a potential explosion.

[VonMackenzie]

I keep a set of jumper cables in my trunk and have used them more times than I'd like to admit. The sequence is everything. Start with red on the dead battery's positive. Then red on the donor car's positive. Black on the donor's negative comes next. The key mistake people make is putting that last black clamp on the dead battery. Instead, clamp it to a clean, unpainted metal surface under the hood of the dead car. You'll see a small spark when you do it, and that's fine—it's happening safely away from the battery.

[McNicole]

Think of it as creating the electrical path step-by-step while controlling where a spark might happen. You begin by connecting the two positive terminals, which are the "source" of the power. Then you establish the ground path. By connecting the final negative cable to the car's body instead of the battery, you are using the vehicle's chassis as a giant ground wire. This ensures that if a spark occurs when the circuit is finalized, it's far from any potentially explosive gases that could be venting from the battery. This method is specified in every owner's manual for a reason.